I’m not going to explain in detail what is ESP8266 because if you have found this post I’m sure you already know it. But just in case, it is an awesome cheap board (less than 4$) with built-in wifi communication (802.11 b/g/n), and SPI, UART. You can also use its processor to run your code.

Wiring:

Use FTDI with 3V3 output. If you face problems with this running on Windows check this link: Unbrick FTDI 232R